Displacement, stress and seismicity in roadway roofs during mining-induced failure

Shen, Baotang; King, Andrew; Guo, Hua

doi:10.1016/j.ijrmms.2007.08.011

Cited by 145 publications

(61 citation statements)

References 3 publications

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“…Coal is an unusual porous material, which has fissures, low intensity strength, heterogeneous texture, and permeability distinguishing it from regular porous materials [6,7]. Gas within the coal seam can strongly affect coal strength, deformation, and fracture propagation, and other mechanical properties [8][9][10]. In underground coal mines, gas is stored in a coal seam mainly in absorbed form or free state.…”

Section: Introductionmentioning

confidence: 99%

“…To evaluate the rock burst liability properly, the so-called bursting liability indicators are employed. The use of a bursting indicator is a good way to evaluate the coal bursting potential, including elastic strain energy index (W ET ), bursting energy index (K E ), uniaxial compressive strength (R c ), the Bursting Efficiency Ratio (η), the Rheologic Ratio (θ), Failure Duration Index (Dt), and the Bursting Energy Index (BEI), (W CF ) [8,[13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

Zhao

Kaunda

2018

Energies

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When coal mines exploit deep seams with high-gas content, risks are encountered due to the additional high likelihood of rock bursting potential problems. The bursts of coal pillars usually lead to severe fatalities, injuries, and destruction of property, including impeding access to active mine workings underground. The danger exists given that conditions in the already highly brittle coal material can be exacerbated by high stress and high gas pressure conditions. It is thus critical to develop methods that improve current understanding about bursting liability, and techniques to forecast or prevent coal bursting in underground coal mines. This study uses field data from a deep coal mine, and numerical modeling to investigate the effects of gas pressure and mechanical compressive stresses on coal bursting liability in high gas content coal seams. The bursting energy index is adopted to determine the coal bursting liability under high gas pressure conditions. The adopted methodology uses a two-staged approach comprising investigating the influence of gas pressure on the bursting liability of coal pillar, and the influence of the gas pressure on the resulting pillar failure mode. Based on numerical simulations of coal pillars, correlations are observed between the magnitudes of gas pressures and the bursting energy index. Irrespective of pillar size, failure time is shortest when the gas pressure achieves a threshold value between 50 kPa to 70 kPa. At 50 kPa, the value of the BEI increases by 50% going from the 4 m pillar to the 6 m pillar. The value of the BEI increases by 43% going from the 6 m high pillar to the 8 m high pillar at 50 kPa. When pillars fail there is a degree of stress relief leading to a reduction in bursting liability. The results suggest that before 50 kPa, pillar failure is largely due to mechanical loading. After 50 kPa, pillar failure is largely due to excessive gas pressures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

Zhao

Kaunda

2018

Energies

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“…Under such a deep geological environment, the underground gateroads frequently tend to produce large and asymmetric deformation. In conventional deformation monitoring of tunnel and underground excavation, the convergence between roof and floor and the convergence between two side walls are measured, while the deformation monitoring of the rest of excavation profile is seldom covered [6][7]. Furthermore, the geometric profiles of gateroads are variable in underground mining and rectangular, trapezoidal and semi-circular arch gateroads are frequently used for different functional purposes and mine-site specific geological conditions [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Development of Laser Scanner for Full Cross-Sectional Deformation Monitoring of Underground Gateroads

Yang¹,

Zhang²,

Liu³

et al. 2017

Preprint

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Abstract:The deformation of underground gateroads tends to be asymmetric and complex. Traditional instrumentation fails to accurately and conveniently monitor the full cross-sectional deformation of underground gateroads. Here, a full cross-sectional laser scanner was developed together with a visualization software package. The developed system used polar coordinate measuring method and the full cross-sectional measurement was realized by 360° rotation of laser sensor driven by an electrical motor. Later on, the potential impact of gateroad wall flatness, roughness and geometrical profile as well as coal dust environment on the performance of the developed laser scanner were evaluated. The studies show that a high-level flatness is favorable in application of the developed full cross-sectional deformation monitoring system. For a smooth surface of gateroad, the sensor cannot receive reflected light when the incidence angle of laser beam is large, causing data loss. Conversely, the roughness surface shows its priority as the diffuse reflection light can be received by the sensor. With regards to the coal dust in measurement environment, the fine particles of floating coal dust in the air can lead to the loss of measurement data to some certain due to scattering of laser beam.

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“…pillar, roof strata and applied support in the field. Any such performance evaluation in the field involves a number of measurements through underground instrumentation and monitoring [7] [8] [9].…”

Section: Introductionmentioning

confidence: 99%

Practical experiences of instrumentation and monitoring for depillaring

Kumar¹,

Kumar²,

Ram³

et al. 2016

Proceedings of the Conference on Recent Advances in Rock Engineering (RARE 2016)

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Abstract-The challenging nature of strata dynamics in and around goaf edge of a depillaring operation warrants continuous vigilance over the dynamics for a safe and efficient working. Depending upon the nature of the working and surrounding rock mass, a variety of geo-technical instruments are, generally, deployed for the vigilance. Selection of positions and installation of these instruments involve good understanding of behavoiur of the associated rock mass, but continuous monitoring of their observations becomes an important issue. In a conventional depillaring working, most of the observations are monitored manually, which may lead to safety threat and unsafe design of the mining structures. Some of the observations of a data-logger based monitoring are proved to be very useful, but the involved financial constraints have restricted its large scale application. Simple incorporation of an electronic continuity circuit in the single point borehole extensometer is known as auto warning tell-tale (AWTT), which has enabled to watch a given value of the roof lowering continuously. This ability of AWTT has proved to be an advantage while depillaring: especially mechanized depillaring. However, it requires a vital input about the rock mass behaviour: the limit of strata deformation to trigger and flashing the alarm light. Explaining the role of design and safety instruments for given conditions of a depillaring panel, this paper provides experience based examples to choose type and positions of the instruments for the monitoring. Briefly discussing the role of combined instrument approach to compensate the error in estimating the rock mass behaviour at the time of instrumentation, the role of continuous monitoring is illustrated with the help of some field measurements in depillaring panels. With the help of a good input of the estimation of strata characteristics in advance, examples of successful use of AWTTs are presented to show its ability to work as a safety instrument. Experiences and measurements found that the AWTT works well under moderate roof strata. Apart from the nature of overlying strata, the field monitoring indicated a need of supervision in observations of this instrument if the working is influenced by barrier effect, leftour pillars/fenders inside the goaf or by a geological structure. Requirement of other supporting instruments are also mentioned on the basis of the noticed problems of this single point measurement below extreme strata conditions (strong and massive or weak and laminated roof strata).

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Displacement, stress and seismicity in roadway roofs during mining-induced failure

Cited by 145 publications

References 3 publications

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

Numerical Assessment of the Influences of Gas Pressure on Coal Burst Liability

Development of Laser Scanner for Full Cross-Sectional Deformation Monitoring of Underground Gateroads

Practical experiences of instrumentation and monitoring for depillaring

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